In gas turbine engines, it is necessary to protect exhaust ducts with an insulating shield in order to prevent heated core gases from damaging the exhaust ducts. Typically, exhaust ducts are made from titanium-based alloys and may have temperature limits of approximately 300° F. or about 148.9° C. Exhaust gases, however, reach much higher temperatures. It is, therefore, necessary to line exhaust ducts with a material that is capable of withstanding the peak temperatures of the core gases and that prevents the exhaust duct from reaching its temperature limitations. Exhaust duct liners are typically made from nickel-based alloys, which have temperature limits of approximately 700° F. or about 371.1° C. In order to alleviate some of the heat from the exhaust gases imparted to the liner, cooling air is passed between the exhaust duct and liner.